The present invention relates to a component mounting method and apparatus for mounting components on mounting objects, such as are used in mounting electronic components on circuit boards, in either provisional mountings or actual mountings, to manufacture electronic circuit boards.
A conventional component mounting apparatus for manufacturing electronic circuit boards is shown in FIG. 9. A component mounting head 102 equipped with a suction nozzle movable up and down 101 for handling an electronic component is supported on an X-Y robot 103, which is moved in two perpendicular directions, X and Y, for moving the component mounting head 102 to a component supply unit 104 and a component mounting unit 105. An electronic component 100 supplied by a component supply unit 104 is picked up and carried by the suction nozzle 101, and mounted at a prescribed position on a circuit board 106 located in the component mounting unit 105.
The suction nozzle 101 is installed on the component mounting head 102 such as to be movable up and down in order to pick up and mount the electronic component 100. Referring to FIG. 10, a nut 107 provided integrally with a support member 113 for the suction nozzle 101 screws onto a ball screw 108 that is turned in both opposite directions by a motor 109 to cause the suction nozzle 101 to move up and down. When the orientation of the electronic component 100 held by the suction nozzle 101 is improper, the suction holding attitude is corrected by turning the suction nozzle 101 about its axis line by a motor 110.
Some electronic components involve insertion of their parts into the circuit board in order to accomplish the mounting to the circuit board 106. Such electronic components 100 are of various types, including axial components, radial components, odd-shaped components having leads or pins, DIP (dual inline package) type IC chips, and connectors provided with leads.
Of these, electronic components which can be handled by a suction nozzle such as described above include DIP IC chips which have a flat upper surface and connectors. For other electronic components, mounting devices are used which have component handling tools especially adapted to those components, respectively.
In any case, the electronic component 100 is held, picked up, and handled by a suction nozzle 101 or other component handling tool. When insertion is involved in mounting the component to a circuit board 106, it is necessary, simultaneously-with positioning the electronic component 100 at the prescribed position on the circuit board 106, to bring the electronic component 100 straight up to the circuit board 106 in a condition wherein multiple pins or leads or other insertion parts in the side of the electronic component 100 all correctly correspond to insertion holes 112 in the side of the circuit board 106, and to apply pressure in a condition where these are in mutual contact, thereby inserting the leads 111 into the insertion holes 112.
Such positional relationships are not always set up properly, however, and failures sometimes arise due to faulty positioning. In order for the insertion described above to be performed in the right amount without fail, it is necessary to cause the electronic component 100 to make contact with the circuit board 106, and to push it in, in the prescribed condition. However, with a drive effected by the ball screw 108 described earlier, there is very little resistance when the electronic component 100 is pressed, whereupon the pressing force cannot be finely controlled, and pressing tends to become excessive. It is also difficult to discern from the resistance, etc., in the insertion operation, whether the leads 111 are inserted or not inserted in the insertion holes 112. In addition, there is also play in the part that screws into the nut 107 that converts circular motion to linear motion, and there are effects produced by backlashes, whereupon appropriate measures cannot be taken that correspond to whether the insertion condition is proper or faulty.
Because of these problems, excessive pressing is easily administered, especially when the leads 111 or other insertion parts are not correctly inserted in the insertion holes 112 in the circuit board 106, whereupon either the electronic component 100 or the circuit board 106 or both are damaged by breaks or cracks, which damage causes a decline in the production yield of the electronic components and the circuit boards.
In other cases where it is necessary to press the suction nozzle 101 against the electronic component 100, or where it is necessary to apply pressure to mount the electronic component 100 to the circuit board 106, similar problems arise because the pressing force cannot be adequately controlled.
An object of the present invention is to provide a component mounting method and apparatus, with which a component can be mounted without excessive pressing.
In order to accomplish the above object, the present invention provides a component mounting method wherein a component supplied by a component supply unit is picked up, carried, and mounted on a mounting object located at a component mounting position, using a component handling tool that is supported by a moving mechanism and is moved to the component supply unit and a component mounting unit, characterized in that: the component handling tool is linearly moved up and down for performing component pick-up and mounting actions by feed-back control of a linear motor, wherein, when the component handling tool needs to be moved down for picking up a component or for mounting a component held on the component handling tool on the mounting object, the linear motor is controlled to effect a downward movement of the component handling tool, and when contact is made between the component handling tool and the component or between the component and the mounting object, upon which changes in control information of the feedback control of the linear motor are detected, control of the linear motor is switched to a pressing operation, whereby the component is picked up or mounted in a predetermined pressed condition.
Thus the component handling tool is moved to the component supply unit or component mounting unit by the moving mechanism, whereupon, whether performing component pickup at the component supply unit or component mounting in the component mounting unit, such can be accomplished with an up and down movement by the linear action of a linear motor on the moving mechanism. With the feedback control of this linear motor, the component handling tool prior to holding the component and/or the component held by the component handling tool is brought close to the component and/or the mounting object, in order to pick up or mount the component, by controlling the linear motor to effect a downward movement of the component handling tool, and contact therewith is first effected. When contact is made, there is a change in the control information due to the targeted position having been arrived at. The point in time where contact was actually made can be detected by the change in the control information at this time.
Thereupon, at the point in time where that control information changed, the linear motor is switched from a downward moving operation to a pressing operation, and the holding or mounting of the component in the prescribed pressed condition is completed. When that is done, it is possible to definitely effect the holding and/or mounting of the component, under prescribed pressing, while preventing contact faults or floating, and without damaging or breaking. either the component or the mounting object by subjecting either to an excessive load. Also, in cases where the component mounting involves insertion in the side of the mounting object, such can be definitely accomplished by the prescribed pressing operation described in the foregoing. Accordingly, production yield is improved for the components and the mounting objects.
The above method can be implemented by using a component mounting apparatus comprising: a component supply unit for supplying components, a component mounting unit for mounting components on a mounting object, and a component mounting mechanism for moving a component handling tool to said component supply unit and said component mounting unit, so that the component handling tool picks up and carries components supplied by said component supply unit and mounts said components on the mounting object in the component mounting unit, wherein: said component mounting mechanism comprises: a moving mechanism for moving said component handling tool to said component supply unit and said component mounting unit; a linear motor for causing said component handling tool on said moving mechanism to move linearly up and down at said component supply unit and said component mounting unit and to cause said component to be picked up and mounted; and a controller for feedback-controlling said linear motor, such that, when the component handling tool needs to be moved down for picking up a component or for mounting a component held on the component handling tool on the mounting object, the linear motor is controlled to effect a downward movement of the component handling tool, and when contact is made between the component handling tool and the component or between the component and the mounting object, upon which changes in control information of the feedback control of the linear motor are detected, control of the linear motor is switched to a pressing operation, whereby the component is picked up or mounted in a predetermined pressed condition.
The method described above can be thereby achieved stably and automatically according to a prescribed program.
The component mounting method according to another aspect of the present invention is characterized in that the component handling tool is linearly moved up and down for performing component mounting actions by feed-back control of a linear motor, wherein the linear motor is controlled to effect a downward movement of the component handling tool for bringing the component held by the component handling tool closer to the mounting object until after an insertion part of the component has been inserted in a corresponding hole in the mounting object, and when contact is made between the component and the mounting object in a predetermined condition, upon which changes in control information of the feedback control of the linear motor are detected, control of the linear motor is switched to a pressing operation, whereby the component is mounted in a predetermined pressed condition.
Thus the point in time where the body of the component, in the prescribed insertion condition, actually contacts the mounting object can be ascertained, the downward moving operation can be switched to a pressing operation at that point in time, and so the component can be definitely mounted in the prescribed pressed condition, while insertion faults are prevented.
Such a method is well suited to components having leads, such as connectors. The controller controls the linear motor such that the component handling tool is lowered for bringing the component held by the component handling tool close to the mounting object until the insertion parts of the component make contact with the mounting object, and is further lowered, until after the insertion parts have been inserted in the mounting object. Upon detecting changes in the control information when the body of the component contacts the mounting object in a predetermined insertion condition, control of the linear motor is switched to a pressing operation.
In the mounting of a component held by a component handling tool that involves insertion in a mounting object as in the case described above, it is possible, from the control information and the position of the linear motor corresponding thereto, to determine whether the insertion is proper or faulty, based on positional discrepancies between the insertion parts of the component and the insertion holes in the mounting object, in terms of height abnormalities. Such determinations can be accomplished automatically by determination means which receive the information. Based on this determination, when the component insertion is faulty, the mounting operation for that same component can be repeated, whereupon it is possible to avoid damaging the components or mounting objects by forcing an insertion operation without correcting an insertion fault, or to avoid discarding the component as a faulty component.